1. Field of the Invention
The present invention relates to a display device. Further, the present invention relates to an electronic device including a display device.
2. Description of the Related Art
A display device that displays a stereoscopic image using a binocular parallax is known. Such a display device is configured to display, on one screen, an image to be seen from the position of the left eye of a viewer (an image for left eye) and an image to be seen from the position of the right eye of the viewer (an image for right eye). The viewer sees the image for left eye with the left eye and the image for right eye with the right eye and is thus allowed to see a stereoscopic image.
For example, in a glasses system, an image for left eye and an image for right eye are alternately displayed on a screen of a display device in synchronization with a shutter provided in a pair of glasses, whereby the left eye of a viewer is allowed to see only the image for left eye and the right eye of the viewer is allowed to see only the image for right eye. Thus, the viewer can see a stereoscopic image.
A parallax barrier system allows viewing of a stereoscopic image with naked eyes. In a display device using a parallax barrier system, a screen is divided into a number of regions for right eye and regions for left eye (e.g., strip-like regions adjacent to each other), and a parallax barrier is provided to overlap with the boundaries of the regions. An image for right eye is displayed on the regions for right eye, and an image for left eye is displayed on the regions for left eye. With the parallax barrier, the regions for displaying the image for right eye are hidden from the left eye of a viewer and the regions for displaying the image for left eye are hidden from the right eye of the viewer; consequently, the left eye is allowed to see only the image for left eye and the right eye is allowed to see only the image for right eye. Thus, the viewer can see a stereoscopic image with the naked eyes.
A display device including a switchable parallax barrier for achieving switching between a flat image display mode and a stereoscopic image display mode is known (Patent Document 1).
Further, a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes is known. This light-emitting element is a self-luminous type; therefore, high contrast and high speed of response to an input signal are achieved. Furthermore, a display device to which this light-emitting element is applied and which consumes low power, is manufactured in a simple process, and is easily adapted to the increase in definition and the size of a substrate is known (Patent Document 2).